Graduation date: 2005

Graduation date: 1999

Thesis (M.Phil.)--Hong Kong University of Science and Technology, 2004. / Includes bibliographical references. Also available in electronic version.

No description available.

The major objective of this project was to assess the application of atmospheric pressure microwave induced plasmas to the control of trichloroethene vapour emissions from industrial cleaning processes. Laboratory experiments, chemical modelling and chemical analysis were the three major elements of the project. A typical stream to be treated, as measured at the project test site, was 60 lmin-1 of air contaminated with 2 % trichloroethene vapour. The practical experiments carried out were trichloroethene dissociation by microwave plasma, propane-assisted microwave plasma and conventional propane combustion. Flow rates of 4 � 12 lmin-1, trichloroethene concentrations of 0 � 6 % in air and plasma powers of up to 3 kW were investigated. The processes were simulated using both equilibrium and kinetic modelling in CHEMKIN. Chemical analysis was done using gas chromatography with an electron capture detector, with gas chromatography/mass spectrometry to identify eluted compounds. The destruction and removal efficiencies, by-products, temperature and robustness of each process were investigated. A simple economic and environmental analysis was done, and the results were compared with currently available processes.

Thesis (Ph. D.)--University of Alabama at Birmingham, 2009. / Title from PDF title page (viewed Jan. 28, 2010). Additional advisors: Shane A. Catledge, Joseph G. Harrison, Raymond G. Thompson, Uday K. Vaidya. Includes bibliographical references (p. 75-78).

The introduction of supercritical CO₂ at packed column supercritical fluid chromatography (SFC) flow rates is shown to significantly affect the excitation characteristics of a helium microwave induced plasma (He MIP). In this work, the influence of CO₂ on specific atomic and ionic transitions of Cl, Br, I, P, and S is described. Also presented is the determined relationship between transition energy and degree of signal depression resulting from the introduction of CO₂ to the plasma. Attempts to enhance the emission signals of non-metals by introducing H₂ into a He MIP are discussed. The inadequacy of excitation temperature, ionization temperature, rotational temperature, and electron number density measurements to determine the effect of CO₂ on the excitation characteristics of a He MIP is also described. However, application of kinetic theory and a recently developed theory on charge transfer allows a reasonable series of mechanisms to be developed that describe the excitation processes of a He MIP to which supercritical CO₂ is added. The remainder of this work describes a direct interface between a supercritical fluid extraction (SFE) vessel and an Ar MIP for the purpose of element selective detection. The response of the plasma to the introduction of sample via SFE at a variety of extraction temperatures, pressures, and sample concentrations is presented. / Ph. D.

Thesis (Ph. D.)--University of Alabama at Birmingham, 2008. / Additional advisors: Yogesh K. Vohra, Xu Feng, Jack E. Lemons, Timothy M. Wick. Description based on contents viewed July 8, 2009; title from PDF t.p. Includes bibliographical references.

Orientadores: Jayr de Amorim Filho, Marco Aurélio Pinheiro de Lima / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Física Gleb Wataghin / Made available in DSpace on 2018-08-24T21:57:52Z (GMT). No. of bitstreams: 1 Ridenti_MarcoAntonio_D.pdf: 6265448 bytes, checksum: 384897ffe1b8b10a23a0ab7c3b206b76 (MD5) Previous issue date: 2014 / Resumo: Neste trabalho plasmas não térmicos gerados em pressão atmosférica e sustentados por ondas de superfície em micro-ondas, tendo o argônio como gás de alimentação, foram estudados experimentalmente e teoricamente tendo em vista aspectos pouco compreendidos de suas propriedades físicas e aplicações voltadas ao tratamento de biomassa. Medições da composição elementar e dos parâmetros físicos foram realizados por meio de técnicas de diagnóstico baseadas em espectrometria de massa e espectroscopia óptica de emissão. O sistema físico foi modelado por meio das equações de continuidade das espécies neutras e carregadas, da equação do calor e da equação de Boltzmann dos elétrons, que foram acopladas utilizando um procedimento auto-consistente. Uma vez obtido o quadro geral das propriedades do plasma, foi estabelecida a condição de operação adequada ao tratamento das amostras derivadas de biomassa. O tratamento foi realizado sobre quatro tipo de amostras: lignina, xilana, celulose e bagaço de cana-de-açúcar. Dentre as contribuições importantes deste trabalho podem ser destacadas: (i) a verificação experimental do papel dos íons moleculares do argônio no processo de contração da descarga; (ii) a determinação do perfil axial no plasma dos principais íon positivos e negativos, da densidade e temperatura eletrônicas, da temperatura do gás e da densidade do estado metaestável Ar(1s5); (iii) verificação da seletividade do tratamento a plasma, tendo sido observada uma alteração significativa dos espectros de absorção no infravermelho nos casos da lignina e da xilana, mas não no caso da celulose. Esse último resultado sugere uma rota inusitada para novas tecnologias de deslignificação e síntese de novos materiais a partir de biomassa / Abstract: In this work non-thermal argon plasmas produced at atmospheric pressure and sustained by microwave surface waves were theoretically and experimentally studied in view of their non understood aspects and also the applications aimed at biomass treatment. Measurements of elemental composition and physical parameters were carried by means of plasma diagnostic techniques such as mass spectrometry and optical emission spectroscopy. Plasma modelling based on the self-consistent solution of the continuity equations of the neutral and charged species, the heat equation and the electron Boltzmann equation was developed to describe the plasma properties. Once a complete picture of the plasma behaviour was obtained, a promising condition for plasma treatment was established. Four types of biomass derived material were plasma treated: lignin, cellulose, xylan and sugarcane bagasse. Among the important contributions of this work one may highlight the following: (i) the experimental verification of the crucial role of argon molecular ions in the discharge contraction; (ii) axial profile determination of the main positive and negative ions, the electronic temperature and density, the gas temperature and the metastable state Ar(1s5) density; (iii) important modification of the infrared absorption spectra after plasma treatment in the cases of lignin and xylan, but not in the case of cellulose, suggesting a unexpected route for delignification and new materials synthesis from biomass / Doutorado / Física / Doutor em Ciências